The unacceptably high incidence of poor literacy skills among American young people is a public health crisis that is both insufficiently understood and understudied. Low reading skill in adults is consistently associated with many negative outcomes, including lesser economic success, increased risk of poor mental and physical health, and poor outcomes for offspring (Kutner, et al., 2007; National Institute for Literacy, 2008). There is a growing appreciation that we urgently need to identify the learning mechanisms for those skills that underlie reading comprehension, and to better understand how they fail in low literacy individuals. Our focus is on young adults, but not the predominantly middle class university students who are most often the subjects of reading research in this age range, but a far less restrictive community-based sample obtained from adult education programs, community colleges, organizations that serve young people and from the community at large. Thus, our sample encompasses a wide range of skill levels including many who have or are at risk of dropping out of the educational system after experiencing repeated learning failure. To date there has been remarkably little direct study of learning processes pertaining to literacy skills and the cognitive abilities that make reading comprehension possible. Clarifying the connections between learning capacities and literacy skills is essential for gauging potential for remediation. This project will build on research from our own group and elsewhere showing that poor readers exhibit reliable differences in learning of linguistic and orthographic structure An important innovation of the project is its use of experimental learning tasks to determine connections among capacities for learning in several theoretically important domains of linguistic and orthographic structure. These tasks include probes of (a) learning relationships between sounds of words and word meanings; (b) learning relationships between spellings and word meanings; and critically; (c) learning relationships between sounds and letters; (d) learning for improved efficiency in processing complex syntactic and semantic structures typical of written language. Individual learning profiles derived from the proposed experiments will be related to scores from a comprehensive test battery indexing capacities that are known to differentiate better from less skilled readers within our study population. This will allow us to connect to the existing knowledge base on individual differences in reading comprehension. A second key innovation of the project is to target a large understudied population that is socially and economically important. Whereas most past studies of individual differences in literacy focus on children at early stages of acquisition, our project focuses on older individuals who are products of our primary and secondary schools but who are in many cases unprepared for further education or the demands of the workplace. The prevalence of poor readers in our samples allows us to study the outcomes of atypical developmental trajectories, providing important constraints on current theory. Our research will elucidate mechanisms for the promotion of effective reading skill within this segment of the population. Thus, through improved understanding learner subtypes, this research speaks to the issue of creating more effective learning environments for low-literacy secondary and post-secondary students.